The test firing of a rocket nozzle and insulated aft closure was conducted on a 25-inch diameter uncured propellant solid rocket motor. The nozzle incorporated insulation material at a low area ratio to simulate flow conditions of the Titan III aft closure. Other insulation materials were placed in the test motor aft closure to provide additional information. The insulation utilized was an asbestos fiber reinforced rubber. Variations in processing and cure conditions were incorporated to provide information that might explain anomolous surface recessions in some Titan III firings. Based on the test results, it appeared that the material performance did vary with process history, but an incompatible sample configuration prevented direct comparison of test results to the Titan III application. The uncured propellant test motor performed adequately, providing a 14 second test duration with a 620 psig maximum chamber pressure. The propellant was a 16 percent Aluminum, PBAN binder formulation.